Engine



AM@ 30s w65 w. 4:1. Comm/me EBYP@ ENGINE Filed Sept. l2, 1963 .2 Sheets-Sheet 2 INVENTOR.

WmQ/@EN C". (Qn/o we@ BY MWMLM ATTOENEl/f United States Patent C) 3,269,374 ENGINE Warren C. Conover, Waukegan, Ill., assiguor to 011thoard Marine Corporation, Waukegan, Ill., a corporation of Delaware Filed Sept. 12, 1963, Ser. No. 308,547 6 Claims. (Cl. 123-59) The invention relates generally to internal combustion engines of the two-stroke type wherein each cylinder has its own crankcase -and wherein a charge of combustion air, or `a charge of combustion air-fuel mixture, or a charge of combustion air-fuel-lubricant mixture, is initially drawn into the crankcase and is subsequently discharged from the crankcase into the cylinder in response to cyclical pressure conditions created in the crankcase by reciprocating piston action.

The invention provides for a construction wherein the crankcase, together with the communicatingy inlet port and the transfer passage, are formed to induce flow of any condensed liquid toward the entrance of the transfer passage into the engine cylinder when the engine is operated in its normal poistion, i.e., with the crank shaft in an upright position. As a consequence, paddling, i.e., the accumulation of condensed liquids, is prevented and smoother engine operation is obtained.

The invention also includes provision of a crankshaft including crank-disks which co-operate with each other and with the inner wall of the engine block to dene a crankcase with significantly decreased volumetric capacity, as compared to that of the crankcase of a former engine of corresponding rating. Consequently, increased compression in the crankcase is obtained, thereby also increasing the compression in the associated cylinder. In multi-cylinders, two-stroke engines, the use of such crank-disks also serves the important function of assisting in providing substantially uniform or identical crankcases. This feature is important, as it provides for uniform compression in each of the crankcases and uniform charging of the crankcases from a single or identical carburetors, thereby obtaining smoother and more efficient engine operation.

In one preferred embodiment of :the invention including an upright crankshaft, both the lanti-puddling and increased crankcase compression features of the invention are obtained through use of a crankcase which is defined, in part, by spaced crank-disks, and by forming the charge inlet port to drain any condensate forming in the inlet port onto the lower crank-disk and by forming the transfer passage for draining any condensate on the lower crank-disk and any condensate forming in the transfer passage into the ports communicating with the engine cylinder.

Gther objects and advantages of the invention will become known by reference to the following description and accompanying drawings in which- FIGURE 1 is a plan view, partially broken away and in section, of an engine incorporating various of the features of the invention; and

FIGURE 2 is an elevational view, partially broken away and in section, of the engine shown in FIGURE l.

Shown in the drawings is a multi-cylinder, two-stroke engine 11 comprising yan engine block 13 which includes means defining a series of cylinders 15 and means defining a common crankcase chamber or cavity 17. Supported by the engine block 13 are two or more spaced bearings 19 which journal an upright crankshaft 21 including a series of crank pins 23 equal in number to the number of cylinders 15. Pivotally connected to each crank pin 23 is one end of a connecting rod 25, each of which, at

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its other end, is pivotally connected with a piston 27 operable in one of the engine cylinders 15.

Each of the cylinders 15 has respectively associated therewith a crankcase 29 which is generally closed except for a charge inlet port 31 and a charge transfer passage 33 which communicates with the associated cylinder 15 through ports 35. In accordance with the invention, the crank pins 23 of the crankshaft 21 are supported at their opposite ends by a series of crank-disks 37 which respectively include crankcase dening surfaces 39 which are generally normal to the axis of crankshaft rotation and which extend to adjacent cylindrical wall portions 41 of the wall of the crankcase cavity 17 so as to define the crankcases 29. interposed between the periphery of each disk and the adjacent cylindrical wall portion 41 are sealing means in the form of O-rings 43.

As a consequence of the above-described construction, the volume of each crankcase is reduced, as compared to the volume of a corresponding crankcase embodying a crank arm or lever, thereby obtaining increased compression in the crankcase in response to piston movement. ln addition, as each crankcase is generally of identical configuration, improved multi-cylinder engine performance is obtained.

In the illustrated, preferred embodiment, provision is also made to prevent condensate accumulations in the crankcases. In this regard, each inlet port 31 and transfer passage 33 co-operates with its associated crankcase 29 to induce ow of any condensate into the transfer passage 33 and into the ports 35 extending through the cylinder wall into the associated cylinder. More particularly, the charge inlet ports 31 each include a cavity which is closed by a reed valve assembly 47 or other similar means for permitting charge inflow in response to a relatively low pressure condition in the crankcase and for preventing outflow during conditions of relatively higher pressure in the crankcase. The cavity 45 is delined, at least in part, by a surface 49 which extends from adjacent the periphery of the surface .39 of the lower crank-disk 37 and includes an inclined portion extending radially outwardly and upwardly from the lower crankdisk, i.e., sloping outwardly and in a direction axially of the crankshaft from the adjacent crank-disk toward the center of the associated crankcase.

The transfer passages 33 are each defined, in part, by a passageway which extends away from the periphery of the surface 39 of the above-mentioned lower crank-disk 37 and includes -a portion having an inclined surface 51 extending radially outwardly and downwardly from the disk, i.e., sloping radially outwardly and in Lhe axial direction away from the center of the associated crankcase. Each surface 51 terminates in close proximity to the ports 35 which extend through the cylinder wall and communicate with the associated cylinder 15. The slope of the surface 49 toward the lower crank-disk 37 and the slope of the surface 51 away from the lower crank-disk facilitates drainage from the cr-ankcases of any condensate.

In operation, when the engine is arranged with the crankshaft 21 extending vertically and with crank-disk surfaces 39 forming the bottom walls of the respective crankcases 29, any liquid condensing in the inlet port will flow downwardly along the surface 49 onto the associated crank-disk 37. Subsequently, either by reason of centrifugal action, by action of fast moving gases, or by reason of gravity, such liquid fiows into the transfer passage 33 and down the surface 51 into the ports 35 for introduction into the associated cylinder 15 in company with the ow of the next charge when the associated piston 27 is at bottom dead center. The condensate which represents fuel of low volatility will be burned and, together with all other liquids, will be subsequently exhausted.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

1. In a two-stroke internal combustion engine the combination of means defining a crankcase chamber, spaced bearing means supported by said crankcase chamber defining means, a generally upright crankshaft journalled in said bearings, extending through said chamber and including a pair of spaced crank-disks concentric with, and normal to, the axis of said crankshaft, sealing means between the periphery of said crank-disks and the inner w-all of said crankcase chamber to thereby define a crankcase, a charge inlet port extending from said lcrankcase, said inlet port being defined, in part, by a surface extending from adjacent the lower one of said crank-disks and including a portion extending radially outwardly and upwardly from said one crank-disk, and a charge transfer passage extending from said crankcase for communication with an engine cylinder, said transfer passage being defined, in part, by a surface extending from adjacent to said lower one of said crank-disks in spaced relation to said surface defining said inlet port and including a portion extending radially outwardly and downwardly from said one crank-disk.

2. A two-stroke Ainternal combustion engine including an engine block including means defining a cylinder, means defining a crankcase cavity extending from one end of said cylinder, said crankcase having inner cylindrical wall portions, means defining a charge inlet port communicating with said crankcase chamber, means defining a transfer passage communicating with said crankcase chamber and including a transfer port communicating with said cylinder, and spaced bearing means having an axis concentric with said cylindrical wall portions, a piston reciprocally carried in said cylinder, a connecting rod pivotally connected at one end to said piston, a crankshaft journalled in said bearing means and including a crank pin pivotally connected to the other end of said connecting rod and a pair of crank-disks concentric with the axis of said crankshaft and supporting said crank pin, and sealing means between the periphery of said crank-disks and said cylindrical wall portions, said charge inlet port being defined, in part, by a surface extending from adjacent to one part of the periphery of one face of one of said crank-disks and including an inclined portion extending radially from said one disk and sloping in one direction along the axis of said crankshaft, and said transfer passage being defined, in part, by a surface extending from adjacent to one part part of the periphery of said one face of said one crankdisk and including an inclined portion extending radially from said one crank-disk, sloping in said one direction along the axis of said crankshaft, and terminating adjacent to said transfer port.

3. IIn a two stroke internal combusti-on engine, the -combinati-on of means defining a crankcase, spaced bearing means supported by .said crankcase, a generally upright crankshaft supported by said bearing means and extending through said crankcase, said crankshaft .including a surface extending transversely with respect to the axis between said bearings and having spaced first and second parts, a charge inlet port extending from said crankcase and having a surface extending from said first part `of said crankshaft surface with la portion extending radially outwardly and upwardly from said first part, and a charge transfer passage extending fr-om said crankcase for communication with an engine cylinder and having a surface extending from said second part of said crankshaft surface with a portion extending radially outwardly and downwardly from said second part.

4. In a two-stroke internal combustion engine, the combination of means defining a cylinder, means der-fining a crankcase extending from said cylinder, spaced bearing means supported by said crankcase, a crankshaft journalled by said bearing means and extending through said crankcase, said crankshaft including a crank-disk extending normal to the axis between said bearings, a charge inlet port extending from said crankcase and having a surface extending from one part of the periphery of one face -of said crank-disk, said surface having a portion extending radially of said axis and sloping in one direction along said axis, and a charge transfer passage extending from said crankcase and communicating with said cylinder, said transfer passage including a transfer port communicating with said cylinder and a surface extending from .a second part of the periphery of said crank-disk face with a portion extending radially of said' axis, sloping in said one direction along said axis, and terminating adjacent to said transfer port.

5. In a two-stroke internal combustion engine, the combination of means defining a crankcase, spaced bearing means supported by said crankcase, a crankshaft jou-rnalled in said bearing means and extending through said crankcase, said crankshaft including a pair of spaced crank-disks extending normal lto the axis between said bearings, a charge inlet port extending from said crankcase and having a surface extending from one part of the periphery of -one face of one of said crank-disks, said surface having an inclined portion extending radially of said axis and sloping in one direction along said axis, and a charge transfer passage extending from said crankcase for communication with an engine cylinder and having a surface extending from a second pa-rt of the periphery of said one face of said one crank-disk and having an inclined portion extending radially of said axis and sloping in said one direction along said axis.

6. An engine in accordance with claim 5 wherein said crankcase includes cylindrical wall portions a-d-jacent to said crank-disks, .and including sealing means extending between the periphery of said crank-disks and said cylindrical wall portions.

References Cited by the Examiner UNITED STATES PATENTS 1,026,849 5/1912 Coffin 1213-59 1,201,242 10/ 1916 Berlize 123---5 9 2,442,217 5/1948 Smith 1'23-73 2,443,957 6/ 1948 Herrington 123-73 MARK NEWMAN, Primary Examiner.

W. E. BURNS, Assistant Examiner. 

3. IN A TWO STROKE INTERNAL COMBUSTION ENGINE, THE COMBINATION OF MEANS DEFINING A CRANKCASE, A SPACED BEARING MEANS SUPPORTED BY SAID CRANKCASE, A GENERALLY UPRIGHT CRANKSHAFT SUPPORTED BY SAID BEARING MEANS AND EXTENDING THROUGH SAID CRANKCASE, SAID CRANKSHAFT INCLUDING A SURFACE EXTENDING TRANSVERSELY WITH RESPECT TO THE AXIS BETWEEN SAID BEARINGS AND HAVING SPACED FIRST AND SECOND PARTS, A CHARGE INLET PORT EXTENDING FROM SAID CRANKCASE AND HAVING A SURFACE EXTENDING FROM SAID FIRST PART OF SAID CRANKSHAFT SURFACE WITH A PORTION EXTENDING RADIALLY OUTWARDLY AND UPWARDLY FROM SAID FRIST PART, AND A CHARGE TRANSFER PASSAGE EXTENDING FROM SAID CRANKCASE FOR COMMUNICATION WITH AN ENGINE CYLINDER AND HAVING A SURFACE EXTENDING FROM SAID SECOND PART OF SAID CRANKSHAFT SURFACE WITH A PORTION EXTENDING RADIALLY OUTWARDLY AND DOWNWARDLY FROM SAID SECOND PART. 